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CONTRAST AGENTS
3rd Radiopharmaceuticals
3rd Year Pharmacy
2016-2017
Radiography and Computed
Tomography
A photographic film containing a •
radiographic image is properly called a
radiograph, although it is commonly
referred to as an x-ray or a film. The
relative difference between the light and
dark areas on a radiographic image
reflects what is called radiographic
.contrast
Contrast media
Any agent or compound administered to a •
patient to improve the visualization of an
.organ or tissue is called a contrast agent
Contrast agents can be classified as •
negative or positive. Air and other gases
are negative contrast agents because they
render a structure, such as the gut, more
translucent. An agent that increases the
radiographic opacity of an organ or tissue
.is a positive contrast agent
• Most contrast agents used in diagnostic
radiology are positive contrast agents.
An ideal radiographic contrast agent should
have the following properties
,elbaliava ylidaer )a( •
,evisnepxeni )b( •
ta scitsiretcarahc noitprosba yar-x tnellecxe )c( •
,ygoloidar citsongaid ni desu seigrene yar-x eht
,yticixot laminim )d( •
,ecnatpecca tneitap )e( •
,ytilibats lacimehc )f( •
on dna ytisocsiv wol htiw ytilibulos retaw-hgih )g( •
dna ,stceffe citomso tnacifingis
evitceles rof deretsinimda eb ot ytiliba eht )h( •
noitercxe dna ekatpu eussit
Barium Sulfate BaSO4
Barium sulfate is a nearly ideal contrast •
agent for oral and rectal studies of the GI
tract. It produces a metal-like density on
radiological studies, is inexpensive, and
when properly utilized, has minimal patient
morbidity and mortality. While various
water-soluble barium compounds are quite
toxic, barium sulfate is an insoluble white
power that is a colloidal suspension in
.water
Magnetic Resonance Imaging
Many contrast agents used for MRI are •
extracellular paramagnetic agents. The
primary paramagnetic metal ion used is
gadolinium, a rare earth element.
nehw mrof )3Gadolinium ions )Gd+
M hydrochloric acid and 0.05 ni deraperp
are extremely effective for enhancing
.water proton relaxation rates
All intravenous gadolinium complexes are •
hypertonic when compared with plasma.
The most common side effects are
headache, nausea, dizziness, taste
.perversions, and vasodilation
ULTRASOUND CONTRAST
AGENTS
Contrast agents are not used for most •
diagnostic ultrasound examinations.
Because ultrasound relies on the detection
of sound waves reflected from tissue
interfaces, gases can create prominent
acoustic interfaces near body tissues and
.can be adapted for use as contrast agents
Perflutren
octafluoropropane •
is a volatile gas that •
efficiently reflects sound
waves. This gas is
encapsulated as a protein
or lipid microsphere that
is generated when a
solution of protein or
lipids is agitated with the
gas immediately prior to
.use for cardiac